Re: Rayleigh Water Test (Was: Re: [ATM] 30" Flats)

["Don Clement" <clement.focuser@verizon.net>]

> Ingalls addressed this in a article in Scientific American.  The primary
> problem seemed to be vibration from outside sources.  He noted that the
> train on the track some distance away, caused ripples in the fringes when
> using it to test a flat.  One suggestion was to use a very viscous liquid,
> heavy oil etc, and dampen the liquid flat well.

Another suggestion is to isolate the liquid flat. There are commercial
optical bench systems that use compressed air with dampened pistons or a
simple solution is to use a sandbox with inner tube isolators see:
http://www.jfairstein.com/SOH.html

Don Clement
Running Springs, California

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